Just shock alone will have a mouse seem dead, but that alone can be fatal. Warmth dark, and quiet is what it needs most.
I would thingk24 hours of destress time it would come around. Problem still remains, if a cat gets hold of a mouse, it may not cause any superficial injuries but can easily cause internal injuries. Breathing is alive though in any event, you might give it another 12 hours, and see if there is any improvement or simply goes over the rainbow bridge.
If it does respond,it will likely be dehydrated and could use an electrolyte like pedialyte. Clean bottled water can substitute.
No foods to this point, dealing with shock and dehydration are first steps, then you might see if it will eat something like a piece of cucumber,watermelon, or baby foods.Jar lids make good food and water bowls.
Like you, I wouldn't get hops up, most of these cases end in fatality. If it should recover and regain strength, I do suggest releasing your little friend in some protected place well away from the house. Survival rate trying to keep them captive is about two weeks.